-LRB- CNN -RRB- -- Larry Smith 's desire to make sure he 's alive to watch his grandchildren grow up was his light bulb moment .

`` I was on the path to not living old and this bothered me , '' he said . `` I want to live long enough to see my young grandkids reach big milestones like graduate from school and get married , or even enjoy simple activities like playing in the yard with them . My grandkids mean the world to me . ''

The 63-year-old epidemiologist from Jackson , Mississippi , recently dropped 58 pounds in a 12-week fitness challenge involving 200 people from the Mississippi governor 's office , state legislature workers and civilians .

`` When they announced I was the winner of the challenge , it was a very emotional experience for me , '' Smith said .

`` I 've never won any kind of athletic event , and it felt like a huge achievement to do it , '' he said .

Smith , who is 5-foot-10 , started the boot camp at 261 pounds and with much hesitation .

`` During the first day of the program I thought I would n't be able to keep up with it because it felt very intimidating and I worried about my weak knees , '' he said .

Smith has struggled with his weight most of his adult life . Before the fitness program , he led a very sedentary lifestyle . He often felt sluggish , lacked energy and felt `` miserable . '' He always dreamed of losing weight , but kept putting it off .

`` By nature , I think many people are procrastinators , and losing weight was something I always wanted to do but was on my procrastination list , '' he said .

The grandfather of three said an e-mail in his work inbox announcing the `` Fit 4 Change Mississippi Fitness Challenge '' was the final push he needed to jumpstart his journey toward a healthier lifestyle .

`` I had known people who participated in the challenge last year and were successful at it , so I thought I 'd give it a try , '' he said . `` I thought it would be worth it for both me and my grandkids . ''

The program was led by Mississippian Paul Lacoste , a former pro football player turned fitness coach , with a vision to help slim down the Magnolia State , which has an adult obesity rate of 33 % - the highest in the United States .

Participants shed a collective 3,043 pounds and 714 inches from their waists by the end of this year 's challenge .

`` The fitness event was one of the hardest things I have ever done in my life , '' Smith said .

`` Paul worked us really hard during our early morning workout sessions and pushed us to our limits , '' he said .

Weight lifting and various cardiovascular exercises were a major part of the fitness plan . Smith and other participants met four days a week for intense one-hour workouts .

Before the challenge started , Smith had high blood pressure , high sugar glucose levels and did not eat well-balanced meals .

After he started the fitness challenge , he added healthy food to his diet , such as fruits , vegetables , fish and chicken , and he eliminated fatty foods and red meats .

`` One of my favorite things to add to food is mayonnaise , but I substituted it with Greek yogurt during the program and this helped me reduce calories , '' he said .

`` I 'm still eating the yogurt , and enjoy it . ''

Smith said the first few weeks of the program were the most challenging , but after a while he adjusted to his new routine and diet and appreciated the opportunity to get fit .

`` It took a lot of effort for me to change my lifestyle , but once I started seeing the pounds shed away , it gave me the motivation I needed to keep going , '' Smith said .

Smith said his goal was simply to get in shape , and he never aspired to win the fitness challenge . He was pleasantly surprised when he did . His blood pressure and sugar glucose levels are normal now , and he feels much better since dropping his weight .

Since the program has ended , he continues to work out and has dropped eight more pounds .

`` I just joined the ` Y , ' signed up for kick boxing , step and Pilates classes and continue to both walk and run every day , '' he said .

`` Paul 's program was the jumpstart I needed , and now I am continuing my weight loss journey on my own , '' he said .

Smith said everyone needs to find their own way to a healthy lifestyle and says his best advice is to `` just do it , '' find something you like and do n't procrastinate or `` wait for tomorrow '' like he once did .

`` I look forward to spending many healthy years into the future with my grandkids , and am glad I am taking the necessary steps to do it , '' he said .

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Larry Smith dropped 58 pounds in 12 weeks and explains how he did it

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`` I was on the path to not living old and this bothered me , '' he said

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Smith : Exercise and a healthy diet are both key to losing weight